Color filter is an indispensable constituent of liquid crystal display device and solid-state imaging device. In recent years, the liquid crystal display device has been required to achieve higher image quality, improved contrast and improved color purity, as compared with the devices required for the conventional ones having been used for television set and monitor. As for a colored photo-sensitive composition used for the color filter, efforts have been made on improving the contrast, by using a pigment particle of smaller size (see Patent Literature 1, for example). Also the color filter for the solid-state imaging device has been required to reduce non-uniformity of color for higher resolution, so that the color filter has been becoming more important to disperse a fine pigment having a small particle size without producing secondary aggregate.
Recent color filters, in particular the color filters for the liquid crystal display device, have been required to improve the color purity, and this needs increase in the content of pigment. Meanwhile, the color filters for solid-state imaging device have been required to reduce stray light due to scattering, as one measure for improving the resolution. It has therefore been a strong demand to thin the colored layers, so that increase in the content of pigment is also necessary in manufacture of the color filters for solid-state imaging device.
In order to increase the content of pigment, it is necessary to increase the pigment concentration in the colored photo-sensitive composition. However, too high pigment concentration inevitably decreases the content of a resin dispersant or a photo-sensitive component (monomer, polymerization initiator, etc.) in the colored photo-sensitive composition, so that the developability may degrade, and the patternability may degrade. In particular, the color filters for the solid-state imaging device, with an extremely reduced pattern size aimed at increasing the number of pixels and reducing size, have been suffering from degradation in developability (suppressive performance for residue in unexposed area).
Meanwhile, there have been known techniques of applying a comb-shaped resin composed of a trunk polymer having a cationic group, or a graft polymer composed of polyallylamine (see Patent Literatures 2, 3, for example). As a method for forming a pattern, there has been known a method for forming a positive pattern using a photo-acid generator and a resin which is improved, by action of an acid, insolubility into an alkali developing solution (see Patent Literature 4, for example).